Momentum type transducers have been utilized to input mechanical energy into a substrate in order to have the substrate move and function as a distributed mode loudspeaker. U.S. Patent to Vincent et al. U.S. Pat. No. 7,386,144 has taught that an inertial type acoustic transducer can do work of this nature using an output disc mechanically attached to a substrate via a receiver using mechanically interlocking tab on the output disc and the receiver. U.S. Pat. No. 5,335,284 to Lemons for Coneless, No-Moving-Part transducer mechanically couples the transducer to the substrate and teaches of a loudspeaker affixed to a wall via a protruding screw forming part of the loudspeaker and which screw, screws into the substrate. Oser U.S. Pat. No. 7,418,108 also teaches of an inertial type transducer. Equally User references a threaded stud protruding from the voice coil actuator or inertial type momentum driver which stud is used as a part of the mounting means or means to affix the transducer to the substrate which negatively affects stack up height of the invention.
As the voice coil actuator or inertial type momentum driver all use varieties of magnetic motors, additional power to perform work is an advantage. Power typically does require the use of magnets which can vary in their capacity to do work by way of their formulation, materials and manufacture. As novel aspects of the art cited herein does include integrating the inertial type audio transducer described into other products, within walls and generally in closed locations, high powered magnets such as neodymium may be considered but are not exclusive to this patent as many other magnet formats may be used such as but not limited to ceramic type magnets. Magnet materials are however sensitive to temperature and would have a propensity to demagnetize or loose efficiency should temperatures rise in the general area of the magnet as a result of electro mechanical work being done. Heat dissipation then becomes a problem as the voice coil windings may get very hot, spread this heat into the magnet structures and demagnetize the magnet material producing a detrimental effect. High heat can even destroy the voice coil and its windings.
Heat dissipation becomes a critical factor. A novel aspect of this invention is to draw heat out of the affected areas of the inertial type acoustic transducer. Using materials and designs to create a path for heat to be conducted and convected away from the voice coil including its windings, magnets and other heat sensitive components and materials, thus augmenting reliability. This permits compact designs to be engendered without risk where the compactness can create new novel applications as well as improving the performance of the acoustic transducer or voice coil actuator when used in constrained or closed spaces.
Generating a magnet motor which is compact and has a high power output know as the BL product in relationship to its size would be advantageous. Power is being described as product of the current, I, length of coil wire, L and flux density, B so that F=iL{circle around (x)}B. Part of the novelty described herein relates to the size of power density of the magnetic motor used. Power will then translate to more efficient transfer of mechanical energy as well as better fidelity when the transducer is used in association with a substrate to reproduce desired audio content.
Associating the inertial or momentum type voice coil transducer with the correct substrate is also at times non trivial. Substrates can range from a great many different materials. Creating a means to reliably and mechanically soundly the voice coil transducer or inertial type momentum driver with a given material is also important. Materials that can be presented are, by way of example and not for limitation, glass, wood, fiberglass, wall board, metal, ceiling tiles. Ferrous metal surfaces can be commonly found in the environments in wall cladding and modular wall systems or other product housings which, again, are by way of example, signage which would benefit from audio content to improve the quality of communication of specific messages, for example. These substrates or soundboards would otherwise work well with an inertial type acoustic transducer but other problems arise.
These additional challenges relate to the magnetic motor and its internal components which must be arranged to minimize or reduce an externalized magnetic flux field. External magnetic flux would shift the internal components forming the magnetic motor, voice coil, voice coil windings, magnetic gap and motor suspension out of tolerance and optimized placement. This, in turn, would negatively affect the performance of the transducer. It is therefore important for the magnetic circuit envisaged in the present invention to not produce a significant stray magnetic flux field out of the magnetic motor as it would draw the stated components towards to steel substrate and out of position. This would have a direct negative repercussion with regards to sound quality. A magnetic motor forming part of the inertial type acoustics transducer having an internalized flux field is desired an is taught in this invention.
The present invention teaches a novel modular system to create an associative means which mechanically couples the inertial type voice coil actuator using a systematic approach to a variety of substrates and retaining the mechanical parameters for sound propagation and transfer of considerable fidelity. U.S. Publication No. 20060126886 A1 teaches a protruding elongated shaft from an acoustic actuator which couples with another protruding actuator stud protruding from a transducer foot. This produces an excessive stack up height which is a disadvantage for the objective of using the transducer within walls or within products. A novel means of reducing stack height will be presented in this invention. Additionally the system will accommodate a variety of substrates using a dedicated mounting means and providing for additional modalities for affixing the transducer to various substrates without significantly adding stack up height. In a novel fashion, the dedicated mounting means described in this invention will provide for optimized heat dissipation as well.
Retaining axial alignment of the voice coil relative to the magnetic gap in the magnetic motor structure is equally challenging. Vincent et al. U.S. Pat. No. 7,386,144 teaches a double suspension. In the present invention a novel means is introduced to create a suspension means bridging and controlling the axial alignment between the voice coil and associated voice coil wire windings to the magnetic motor, and magnetic motor to housing thereby creating the desired control between all components and hence improving sound quality and eliminating distortion by way of part interference or misalignment. Additionally other means are used to further improve part separation and optimal sound quality using ferro fluids within the magnetic gap.
Those skilled in the art will recognize that improvement in the power handling can be realized by the addition of a magnetic fluid in the form of low viscosity oil, having microscopic ferrous particles such as magnetite, homogeneously suspended in the fluid. The oil-magnetic emulsion is attracted to and held in the magnetic field within the magnetic gap by reason of the magnetic flux across this gap. The magnetic particles hold the liquid phase of the oil within the gap. The viscous magnetic fluid provides a heat dissipating mechanism and a radial restoring force when the voice coil is radially displaced. The restoring force is a result of an unbalanced magnetic force in the fluid when the fluid is not symmetrically displaced within the magnetic gap and coil former. The radial restoring force is typically sufficient to support the mass of the magnetic circuit when its axis is parallel to a horizontal orientation. In the event of substantially larger radial forces that will overcome the radial restoring force of the viscous magnetic fluid, the antifriction bearing acts as a back-up bearing for the voice coil former.